1. Field of the Invention
The present invention relates, in its most general aspect, to the field of electronic circuits and in particular to the field of the electronic circuits comprising components of nanometric sizes.
More specifically, the present invention relates to a method for realizing, in a circuit of the above type, a plurality of electric contacts between elements of nanometric sizes (nanowires) defining the above circuit architectures of a nano-area, and standard electronic components of a micro-area.
2. Description of the Related Art
In such field, an electronic circuit integrated in a semiconductor device can be schematically represented by one or more micrometric regions, or micro-areas, interacting with one or more nanometric regions or nano-areas.
A micro-area comprises, or is defined by, so called standard electronic components such as, for example, capacitor diodes, MOSFET transistors, address devices, logic and memory devices, micro-contacts, or portions thereof.
The sizes of such standard electronic components, usually micrometric or sub-micrometric, depend, in the last analysis, on the wavelength of the photolithographic source employed in their realization, usually not lower than 90 nm.
A nano-area comprises in turn, or is defined by, circuit architectures of nanometric sizes obtained, for example, by means of electronic lithography (e-beam lithography), with SnPT technique (Multi-Spacer Patterning Technology) or by means of imprint lithography (in all the possible versions: Soft Lithography, Nano-Imprint Lithography, Step-and-Flash Imprint Lithography, and Superlattice Nanowire Pattern).
A nano-area can possibly comprise, moreover, housed in such nanometric circuit architectures, molecular devices realized through chemical synthesis, i.e. molecules able to perform specific functions of mechanical, electric or optic nature.
As it is known, in the electronics field, the need of realizing circuit configurations of more and more reduced sizes is particularly felt.
Actually, the advent of constantly more refined technologies has allowed the miniaturization of the circuit architectures and, in consequence, a greater density thereof in the semiconductor electronic devices.
For example, it has been possible to realize, by means of non-photolithographic techniques, arrays of nanowires having a pitch in the order of a few tens of nanometers (circa 30 nm), or still crossbar architectures of nanowires having a density of intersection points of about 1011 cm−2.
Some examples of such embodiments are reported in the publication by N. A. Melosh, A. Boukai, F. Diana, B. Gerardot, A. Badolato, and J. R. Heath, “Ultra High Density Nanowire Lattices and Circuits”, Science 300, 112 (2003), and in that by M. D. Austin, W. Zhang, H. Ge, D. Wasserman, S. A. Lyon and S. Y. Chou, “6 nm half-pitch lines and 0.04 μm2 static random access memory patterns by nanoimprint lithography”, Nanotechnology, 16 (2005). A further embodiment is disclosed in the U.S. Pat. No. 6,128,214 by P J. Kuekes et al.
However, although currently the capacity to obtain nanometric architectures having the above sizes is widespread, the realization of semiconductor devices comprising such architectures has mainly interested, up to now, the experimental aspect.
The substantial absence of a production of such electronic devices on an industrial scale, is mainly due to the difficulty of relating nanometric architectures to standard electronic components, i.e. of realizing a connection interface between nano-area and micro-area of the electronic device.
Although some methods have been developed for the realization of the above connection, as it is reported, for example, in the U.S. Pat. No. 6,256,767 by Kuekes et al. and in the publication by A. DeHon, P. Lincoln and J. E. Savagein, “Stochastic assembly of sub-lithographic nanoscale interfaces”, IEEE Trans. On Nanotec. 2 (3), 165174, (September 2003), such methods are not reliable and industrially profitable.
It would be thus desirable to have a method at disposal for realizing an electric connection between standard electronic components of a micro-area and nanometric electronic components of a nano-area, which is particularly simple, reliable and in line with the currently used technology for realizing circuit configurations of more and more reduced sizes.
Such a method would allow an industrialization on a large scale of high density integrated electronic circuits in a semiconductor substrate.